Method and means for making twist drills



1964 K. 1.. OCONNELL ETAL 3,117,471

METHOD AND MEANS FOR MAKING TWIST DRILLS Filed July 17, 1962 4 Sheets-Sheet l INVEgTORfi. lfE/Y/YETH A. 0' o/wvzu.

JoH/v 5. O'CONNELL 12W d w arr w/vars Jan. 14, 1964 K, O'CONNELL ETAL 3,117,471

METHOD AND MEANS FOR MAKING TWIST DRILLS Filed July 17, 1962 4 Sheets-Sheet 2 INVENTORJ. AE/V/VErH A. 0 'Ca/wvELL 1964 K. L. O'CONNELL ETAL 3,117,471

METHOD AND MEANS FOR MAKING TWIST DRILL-S Filed July l7, 1962 4 Sheets-Sheet s INVENTORS. law/v57 A. 0 CON/WELL JZfi/V 5. U'CdN/VA'LL HTTOIPA/EXS 1964 K. O'CONNELL ETAL 3,117,471

METHOD AND MEANS FOR MAKING TWIST DRILLS Filed July 17, 1962 4 Sheets-Sheet 4 INVENTORJ. KEN/v57 L.0'C0/V/VELL c75/7N 5. O'CaN/VaL United States Patent 3,117,471 METHGD AND MEANS FQR MAKING TWIST DRILLS Kenneth L. Otlonnell, 32 Villa Beach, Cleveland, Ohio,

and John B. OConnell, RD. 4, River Road, Willoughby Hills, Ghio Filed July 17, 1952, Ser. No. 210,568 18 Claims. {(Il. '76--1tl8) This invention relates primarily to the making of twist drills, but the methods and means disclosed herein may be adapted to the mechanical deformation of other blanks or pieces suitable for the production of articles to which a deforming twisting force is applied while the blank or piece is heated within a range suitable for the particular metal or alloy.

The conventional twist drill is provided with a pair of diametrically opposed helically fluted channels. There are various ways in which this drill contour may be achieved. The flutings may be machined to the desired pitch in the drill blank, which is an expensive procedure, and is not an approved method since the flow of planes of the forged, rolled, or extruded stock will be intersected by the machined grooves to produce a structure subject to subsequent fracture where the flow lines intersect the machined surface.

In another method the fluted channels are formed straight by mechanical indentation, such as by pressing or forging, and the blank is thereafter heated to metal working temperature, and then encased in a succession of parallel fitted discs, the twisting force being then applied by successive increments to successive discs while one end of the blank is fixedly gripped, so that the cumulative effeet is expected to produce the desired lead or pitch. This method is cumbersome and inefficient. cuouyim One may attempt to heat a blank, grip one end, and twist the other end but it is difificult to achieve uniform working temperature throughout the length of the blank, and as a result when the blank is twisted the hotter portion will be more deformable than the cooler portion whereupon the torque will be more effective on the hotter portion and the fiuting pitch will not be uniform, but will be inaccurate. This results in a disturbin ly high scrap loss with consequent increase in cost.

Further problems arise in conjunction with the manufacture of drill bits having longitudinal channels therein to convey cooling fluid or cutting oil to the cutting tip of the drill. Since the direct boring of a helical hole is economically unthinkable and quite probably mechanically impossible, the practice heretofore has been to bore the holes straight in the blank before the flutings are formed. In this stage the flutings may also be formed rectilinearly. The bored and fluted blank may then be heated and twisted in the manner described in the last preceding paragraph. As a variation of this technique the hole or holes may be bored. The blank may then be heated and twisted as described, so as to produce a helically extending hole of the same pitch as the ultimate flutings, and the flutings are then machined to the desired pitch in the blank, the blank being set up and carefully 3,1 17,4? 1 Patented J an. 14, 1964 "ice means whereby-problems arising from uneven blank heating are minimized or completely avoided.

Using as an example the twisting of an elongated bit or blank in one stage of the manufacture of a fluted drill, an object of the present invention is to apply to the bit or blank a deforming torque whereby a helically effective twist is applied to, and developed progressively in the blank in an axial direction from one end to the other.

A further object of the invention is to provide methods and means for effecting the object described in the last preceding paragraph while applying a localized heating, the zone of the heat application being advanced progressively from one end of the blank to the other in predetermined synchronism with the application of twisting torque.

A further object ofthe invention is to provide novel and improved methods and means for the manufacture of helically fluted drill bits wherein the fiutings are first formed rectilinearly by forging, pressing, machining, or the like, and the bit is thereafter twisted to the desired helical pitch or. lead. V p

A further object of the invention is to provide novel and. improved methods and means for the manufacture of fluted twist drills wherein helical cooling fluid passages extend from the tip of the shank, the said passages having the same helical pitch as the drill fluting. A further object of the invention is to provide a method and means for economically forming a helically fluted drill having a shank of relatively inexpensive alloy and a working portion of relatively expensive alloy.

Other objects and advantages will be apparent from a study of the following description of one embodiment of the invention, in conjunction with the accompanying drawings, in which: i

FIG. 1 is a simplified plan view of a set-up for forming a twist drill bit having two fluid passages therein;

FIG. 2 is a fragmentary plan view, somewhat enlarged, and before the drill blank is twisted;

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 2;

FIG. 4 is a view similar to FIG. 2 but showing the blank after twisting but before fluting;

FIG. 5 is a top plan view of one embodiment of an apparatus whereby our invention may be put into practice;

FIG. 6 is a side elevational view as seen from below FIG. 5;

FIG. 7 is an enlarged fragmentary top plan view, with parts broken away and in section, showing details of the apparatus of FIGS. 5. and 6;

FIGS. 8, 9 and 10 are sectional views taken respectively on the lines 8-8, 99, and 10-10 of FIG. 7.

FIGS. 1, 2, 3 and 4 show some of the background leading to an understanding of the invention. A motor Zll supplied with current through leads 21 and 22 rotates reduction gearing in housing 23 to operate a pinion 24. The pinion drives a ring gear 25 fixed on a chuck or other gripping means (not shown) adapted to twist a blank 26 when motor 29 is operated. The other end of the blank is fixed in a non-rotatable end head 27, and it is apparent that if the motor is running the blank 26 is being twisted. If the elastic limit of the particular metal or alloy is exceeded at the operating temperature a permanent set of helical character is achieved inthe blank.

Referring to FIGS. 2, 3 and 4 if two drilled passages 28 and '29 are bored in the blank before the above described operation begins, as indicated in FIG. 2, the passages will have acquired the helical pitch shown in FIG. 4 after a specific amount of twist has been imparted. The particular pitch or lead of the helix may be regarded as the distance between the points P1 and P2. in FIG. 4, analogous to the distance between adjoining crests or troughs in a machined screw thread. H

FIG. 4 represents an ideal condition not always achieved heretofore in practice because as previously mentioned hereinabove the whole blank is not always of even temperature from end to end, and a hotter portion will deform more readily than a cooler portion with the result that the pitch will vary. If fluting by machining is then attempted, some of the fluted trough may cut into one of the passages.

Not all drill blanks are bored for cooling passages, but the problem is equally pressing it iluting is first formed in rectilinear manner by forging, machining, extrusion, or otherwise, and the fiuted blank is then twisted to the desired pitch. Here too a non-uniform response to the applied torque will produce an irregular spiral, and non-uniform pitch.

We have discovered a method whereby the above disadvantages may be completely avoided. In our method the blank is not completely heated to Working temperature beforehand but is heated only in a narrow transverse zone which zone is advanced from one end of the blank to the other in synchronism with the application of deforming torque at one end of the blank. By properly relating the speed of advance of the heating zone to the rate of rotation of the rotatable end of the blank a uniform pitch is achieved. The twisting force is effective only in the zone where the elastic limit is exceeded at the particular temperature used and so the proper pitch is imposed and progresses a little at a time under exactly controlled conditions.

It can be seen that if, for example, a two-inch pitch or lead of fiutings is desired, it is only necessary to advance the heating zone longitudinally two inches, while the end of the biank is being rotated through one complete turn. Each cumulative fractional increment of twist is applied with precision since neighboring cooler portions of the blank do not respond to the twisting effect.

A novel and improved apparatus whereby our inventive method is put into operation is shown in FIGS. 5 to 10, with especial reference to the beginning of this description to FIGS. 5, 6 and 7.

A fixed machine bed 32, carries respective housings 33 and 34 at its opposite ends. Housing 33 encloses a motor, gear-reduction mechanism, and two driving connections, all these being not shown since familiar to those skilled in the art. It is sufficient to state that one driv ing connection produces rotation of a collet chuck 35 at a suitable rate, and the other connection produces rotation of a shaft 36, also at a suitable rate, which may not be the same rate as that of the chuck.

Housing 34 encloses supporting means, not shown for carrying the collet chuck 37 which is fixed against rotation. A blank 38, for example for a drill bit, is gripped by chucks 3S and 37. From what has already been said it will be understood that the blank is twisted when chuck 35 is rotated. Chuck 37 may be extendable or retractable to accommodate different lengths of blank, or indeed either housing 33 or 34 may be movable on the bed as in lathe construction.

A carriage 41 is movable on two spaced bars or rods 42 and 43 which are attached to end housings 33 and 34. Bushings or bearings 44 on the carriage slide on the rods 42, 43, as best seen in FIG. 6. The carriage is advanced from left to right (or if desired from right to left, but with appropriate changes) in a manner to be explained hereinafter. The carriage has fixed thereon a heating member 45 which could be an electrically energized unit such as an induction heater, or a torch type fed by a gas or mixture of gases. Those skilled in the art can readily supply suitable heating means which will apply an annular zone heating effect within a narrow zonal range or plane, transverse to the axis of the blank. If heater 45 is an annular flame burner we prefer to use one in which the flame issues through a circumferential inwardly opening slot since this provides the most even heating effect. In this case also we provide a backstop 46 to restrict the actual heating area, and the central opening in this backstop can closely encircle the blank. The backstop position can be made adjustable towards and away from the burner, and can be water cooled through piping 47.

As previously explained the speed of advance of the burner along the blank in correlation with the rate of rotational twist determines the pitch of the twist and in drill bits, for example, the pitch of the fluting varies with the drill diameter. We prefer to vary the speed of advance of the carriage while maintaining the rotary speed of the blank constant, and this is done in the following way.

A second carriage 51 is movable transversely, at right angles to the movement of carriage 41 (FIG. 7). This second carriage moves on a cantilever track consisting of a pair of rods 52 and 53 extending above and spaced from the base 32, being fixed at their inner end in a bracket 54 fixed on the base by rivets or screws 55. At their overhanging ends the rods are joined by a tie link 56. A clutch bar 57 is pivoted at 58 (FIG. 9) in a slot in carriage 51. This clutch bar carries a threaded semi-circular segment 59 which in normal, lowered position engages the upper part of a threaded shaft 66. Obviously when shaft 60 rotates, and the threaded clutch is engaged, the carriage moves appropriately on tracks 52, 53 depending on the direction of rotation of shaft 60. A half-round clutch bar actuator 63 (FIGS. 7 and 9) can be rotated through by a knob 64 to raise the clutch bar 57 against the bias of spring 65 to disengage the carriage 51 from its driving engagement with shaft 60.

Shaft 60 has a bevel gear mesh engagement with shaft 36 previously mentioned. The two bevel gears 66, 67 are pinned to their respective shafts 60 and 36.

The function of carriage 51 is to carry a cam track consisting of the slotted roller guide 68. A roller 69 hangs from carriage 41 (FIG. 6) and has a rolling fit in the slot of guide 68. It will now be evident, referring for example to FIGS. 5 and 7, that with the guide 68 fixed in the angular position shown, if carriage 51 is moved in the direction of the top of the figure, roller 69 and carriage 41 are cammed towards the right. The angular disposal of guide 68 with relation to the longitudinal extension of the base, as determined for example by rods 42, 43, or the blank 33, determines the rate of progress of carriage 41 with its ring heater.

We have provided a scaled segment 72 with graduations which can be calibrated to represent units of lead, such as inches and fractions thereof. By rotation around its attaching pivot 73 the guide 68 can have its edge 68a aligned with any desired graduation on segment 72, after which the pivot is tightened, for example by an Allen head manipulator.

The manner of operation of our device will now be obvious. Stud 73 is slacked off to free the cam bar 68, which is then set at the desired helical lead by aligning the bar with the scale 72, after which clamping stud 73 is tightened. Clutch control knob is rotated to bring the high point of cam rod 63 under clutch bar 57 so as to disconnect carriage 51 from drive shaft 69. The carriage is then withdrawn to its starting point and clutch control knob rotated until the portion 59 of clutch bar 57 engages the mated threads on drive shaft 60. A blank, fluted or bored or otherwise, is clamped in collet chucks 35 and 37 and the heater 45, if of the induction type, is energized. If the heater is of the flame type it is ignited. When a working temperature is reached, which of course will vary with different metals and alloy contents, the motor which drives collet 35 and also shaft 36 is started, and the operation proceeds as hereinabove described. A limit switch may be supplied to stop the motor when carriage 51 reaches a point consistent with the desired length of fluting, or other operation.

it will be apparent that a series of machines can be provided, each machine adapted to operate within a certain range of blank diameters and lengths.

One practical advantage of the use of our machine; in

addition to those hereinabove recited, is that-it permits the manufacture of composite drill-bits having, for example, a shank made from relativelydnexpensive alloy stock, and a fluted working p'ortioninada from relatively expensive high-hardness stock. Heretofore, when manufacture of this type of drill was attempted by then known ethods, for example by heating the whole drill bit and then twisting it, the relatively soft shank end deformed readily and the'hard working portion deformed to a lesser extent. By our method and apparatus only the working portion of the drill bit is heated and twisted.

Further, our invention enables us to twist two drill-bits simultaneously while saving a substantial portion of expensive stock. In the ordinar operation of our machine, as hereinabove'described, when making one drill bit, that portion of the blank or bit which is gripped in each chuck is not finished and the end adjacent the fluttings must be cut off. However we can take a long enough blank for two drill bits, flute it or otherwise twist it over the majority of its length, and then cut it in the middle of the tinted portion to provide two drills with no waste at the fluted end.

As a further example of this saving, we can take two composite blanks or bits, butt weld the relatively expensive ends to form one blank, twist the double-length blank, cut it in the middle, and end up with no waste of the expensive alloy stock.

While we have restricted the description of our invention for the most part to its use in connection with the making of twist drills, it will now be obvious that it can be used with any type of elongated metal article to which a uniform pitch or twist must be applied in the presence of heat.

We have spoken herein about applying a twisting torque to one end of a blank while the other end is gripped in fixed position. Obviously the same result could be achieved by rotating both ends of the blank but rotating one end at a faster rate than the other end, since what is necessary is a rate differential between the blank ends.

We have also spoken of a cylindrical blank, but by our apparatus and method we can process elongated blanks or non-circular cross section, for example elliptical, rectangular, pentagonal, hexagonal, etc. While We have also spoken of processing metal blanks, the teachings of this invention can be applied in working with other materials which are malleable at some temperature above room temperature, for example some of now well-known synthetic plastic materials.

What is claimed is:

1. A method of producing a twist of accurate and uniform helical pitch in a portion of an elongated metallic cylindrical article such as a twist drill blank, said method comprising holding one end of the article in fixed position while applying to the other end of the article an automatically controlled and continuously applied twist ing force, and simultaneously heating the article in a narrow zone transverse to the length of said portions of the article, and causing said zone to be advanced automatically at a uniform rate of speed along the length of said portion.

2. A method as defined in claim 1 including, in combination therewith, the step of controlling the rotational rate of twist in relation to the speed of advance of the heating zone.

3. A method as defined in claim 1 wherein said heating is achieved by directing the heating effect radially inwardly from a circumferentially disposed heat source, and maintaining said heat source at a temperature high enough to raise the metal in the heating zone to within a working range.

4. A method of treating a fluted twist drill blank to position, applying to the other end of the drill blank an automatically controlled and continuously applied twisting force, controlling the location of effectiveness of said force in successive incremental zones progressing along the length of the drill blank, and likewise automatically controlling the speed of progress of the zones with relation to the rate of twist of said other end.

5. A method as defined in claim 4 wherein said control of the locationof eifectivenessvof. the'force is achived by automatically advancing a source of heat along the portion of said drill blank to be twisted,- and restricting the location of effectiveness of the heat to an advancing narrow zone transverse to the longitudinal axis of the drill blank. 1 1

6. A-method or" making a twist drill having a longitudinal helical passage therein, comprising boring an oil center aperture rectilinearly through an elongated cylindrical blank, holding one end of the blank in fixed position While applying to the other end of the blank an automatically controlled and continuously applied twisting force, simultaneously heating the blank in a narrow zone transverse to the length of the blank, and continually automatically advancing said zone along the. length of the blank whereby said passage assumes a helical pitch of a character dependent on the relationship between the rate of twist and the rate of advance of said zone, and finally forming -flutings in the blank surface of a pitch identical with that of said aperture.

7. A method of making a twist drill comprising forming on a longitudinal cylindrical metallic blank one or more spaced fiutings extending rectilinearly along the ultimate working surface, holding one end of the blank in fixed position while applying to the other end an automatically controlled and continuously applied twisting force, simultaneously heating the fluted portion of the blank in a narrow zone transverse to the length of the blank, and continually automatically advancing said zone along the length of the blank whereby said fluted portion assumes a helical pitch of a character dependent on the relationship between the rate of twist and the rate of advance of said zone.

8. Apparatus for producing a twist of accurate and uniform helical pitch in a portion of an elongated metallic cylindrical article such as a twist drill, said apparatus comprising a base, a first gripping means on said base for holding one end of said article in fixed position, a second gripping means spaced from said first gripping means for holding the other end of said article, a first motion transmitting means for continuously and automatica-lly applying a twisting force to said second gripping means, heating means surrounding a narrow transverse zone of said article, and a second motion transmitting means for moving said heating means along said article while said first motion transmitting means is in operation, and means for automatically controlling the movement of said heating means at a uniform rate and in synchronism with the application of said twisting force.

9. Apparatus as defined in claim 8 including, in combination therewith, control means for varying the speed of movement of said heating means relative to the rate of rotation of said second gripping means.

10. Apparatus for producing a twist of accurate and uniform helical pitch in a portion of an elongated metallic article such as a twist drill blank, said apparatus comprising a base, a first gripping means on said base adapted to hold one end of said article in fixed position, a second gripping means spaced along said base from said first gripping means for holding the other end of said article, said second gripping means being rotatable, a driving means adapted to be continuously effective on said second gripping means for rotation thereof, a carriage adjacent to said article, heating means on said carriage disposed to apply heat to said article in a narrow annular zone, and motion transmitting means for automatically moving said carriage whereby to cause said heating means to travel along said article at a uniform rate as said sec ond gripping means is rotated.

11. Apparatus as defined in claim 10 wherein said motion transmitting means is adapted for producing movement of said carriage in controlled relationship to the rate of rotation of said second gripping means.

12 Apparatus as defined in claim 11 wherein said motion transmitting means includes a cam surface effective, by movement thereof, to operatively abut and advance said carriage, and adjustable means for varying the angular relationship between said cam and said carriage to vary the rate of movement of said carriage with respect to the rate of rotation of said second gripping means.

13. Apparatus as defined in claim 12 wherein said cam includes a pivotable elongated track having means for holding it in any one of a variety of preselected positions, said carriage having a roller thereon abutting said track, whereby when said track is moved, following movement of said roller advances said carriage at a rate determined by the angular relationship of said track.

14. Apparatus as defined in claim 13 wherein said motion transmitting means moves said cam and track transversely to the direction of movement of said carriage, and wherein said track is angularly inclined to the direc tion of movement of said carriage.

15. Apparatus as defined in claim 14 wherein said cam is carried on a second carriage which is movable at right angles to the direction of the first said carriage, and wherein said cam is adjustably mounted on said second carriage for preselected variation of the angularity of said track.

16. Apparatus as defined in claim 15 wherein said second carriage carries indicia fixed adjacent to the path of preset adjustment of said cam track, said indicia being adapted to indicate the relationship between the rate of rotation of said second gripping means and the rate of advance of the first said carriage, and consequently to indicate the pitch of the twist imposed on said article.

17. A method of producing a twist of accurate and uniform helical pitch in a portion of an elongated article which is deformable at an elevated temperature, said method comprising holding one end of the article in fixed position while applying to the other end of the article a controlled twisting force, and simultaneously heating the article to-such elevated temperature in a narrow zone transverse to the length of said portions of the article, said zone being continuously automatically advanced along the length of said portion, at a uniform rate.

18. A method of producing a twist of accurate and uniform helical pitch in a portion of an elongated article which is deformable at an elevated temperature, said method comprising applying to the opposed ends of the article respectively controlled twisting forces at different rates whereby to establish a rate difierential between the ends, and simultaneously heating said portion of the article to such elevated temperature in a narrow zonetransverse to the length of said portion, said zone being continuously automatically advanced along the length of said portion, at a uniform rate.

References Cited in the file of this patent UNITED STATES PATENTS 331,739 Stetson Dec. 1, 1885 475,193 Burton et al May 17, 1892 589,576 Rickey Sept. 7, 1897 983,896 Hartel et ai Feb. 14, 1911 1,405,414 Hervig Feb. 7, 1922 1,891,831 Okochi et al Dec. 20, 1932 2,457,132 Delaney Dec. 28, 1948 

1. A METHOD OF PRODUCING A TWIST OF ACCURATE AND UNIFORM HELICAL PITCH IN A PORTION OF AN ELONGATED METALLIC CYLINDRICAL ARTICLE SUCH AS A TWIST DRILL BLANK, SAID METHOD COMPRISING HOLDING ONE END OF THE ARTICLE IN FIXED POSITION WHILE APPLYING TO THE OTHER END OF THE ARTICLE AN AUTOMATICALLY CONTROLLED AND CONTINUOUSLY APPLIED TWISTING FORCE, AND SIMULTANEOUSLY HEATING THE ARTICLE IN A NARROW ZONE TRANSVERSE TO THE LENGTH OF SAID PORTIONS OF THE ARTICLE, AND CAUSING SAID ZONE TO BE ADVANCED AUTOMATICALLY AT A UNIFORM RATE OF SPEED ALONG THE LENGTH OF SAID PORTION. 